Hi Mandy, MethodType::fromMethodDescriptorString​ (and the three arg Class.forName) requires that a class loader be supplied. Perhaps for the thing consuming StackWalker it’s not possible to reproduce a MethodType (or components of) from the descriptor string much like it may not possible to reproduce the declaring class from the class name string, hence the need for RETAIN_CLASS_REFERENCE?
If i understand you correctly i think you are saying the method descriptor is more useful for informational (logging say) purposes? Paul. > On 28 Aug 2017, at 15:57, mandy chung <[email protected]> wrote: > > Method signature is missing in the StackFrame API. This proposes to add > StackFrame::getMethodDescriptor method to return the method descriptor in a > stack frame. > > Webrev at: > http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8186050/webrev.00/index.html > > There are a couple options how to present the method signature in the API > level: > 1. Class<?>[] getParameterTypes() and Class<?> getReturnTypes() similiar to > what java.lang.reflect.Method has. > 2. java.lang.invoke.MethodType > 3. a String representation (i) comma-separated list of the method's formal > parameter types (ii) bytecode method descriptor as specified in JVMS > > Returning Class<?> instance should require to add a new StackWalker option to > access to the parameter types and return type for option #1 and #2. > StackFrame::getDeclaringClass requires the stack walker to have the > RETAIN_CLASS_REFERENCE capability. > > Option #2 returning MethodType is handy while java.lang would reference a > type in java.lang.invoke. > > Option #3 requires the caller to parse the return string and call > Class.forName to get the Class<?> instance. OTOH > MethodType::fromMethodDescriptorString​ method that returns MethodType from a > bytecode method descriptor string. > > Method signature is for information for typical cases. Getting Class<?> for > the parameter types and return type would be a niche case. I think returning > the method descriptor string is a good option - keep the API simple and can > use MethodType::fromMethodDescriptorString​ to get back the types if needed. > > thanks > Mandy
